Well the main complaint is the impossibility of their escapes. One example is with them on the knees of a rock monster and they aren't somehow not thrown off like rag dolls. Also with them falling hundreds of feet on a piece of bridge and then the big goblin falls on top of them and they all walk away without even a scratch.
Lets not forget the added silliness that was not even in the book. With Radagast's bunny sleigh, with the bird poop on the side of his face and him smoking Gandalf's pipe and reacting like it gets him high, and the smoke coming out of his ears. A troll using Bilbo as a hanky and he ends up covered in snot. One of the trolls is silly with his crossed eyes and squeaky voice.
Constantly Thorin saying Bilbo doesn't belong, because the filmmakers believe we have to be constantly reminded that he doesn't so the end is the pay off that he finally does.
Azog looked unfinished, because the actor playing the part was changed to a CG character late in production.